Isostatic Model Research Articles

The impact of lateral density variation model in the determination of precise gravimetric geoid in mountainous areas: a case study of Iran

The existence of topography above the geoid violates the basic assumption of Stokes’ formula for the determination of the geoid. Usually a constant density of 2.67 g cm−3 is used in the determination of the geoid. However, we know that the density of the topographical mass departs by about 10–20 per cent from the actual mean value of the crustal density. Iran has one of the largest relief and density variations in the world and the geoid computation in this area is affected the most by topographical density effects. The influence on the geoid height coming from the actual and Pratt-Hayford's isostatic models are studied. Numerical results show that the differences in the geoid height due to actual and isostatic density models can reach up to 0.22 and 0.29 m, respectively, which is not negligible in a precise geoid determination with centimetre accuracy. Our results suggest that the effect of topographical density lateral variations is significant enough and ought to be taken into account specially in mountainous regions in the determination of a precise geoid model.

The structure, isostasy and gravity field of the Levant continental margin and the southeast Mediterranean area

A 3-D layered structure of the Levant and the southeastern Mediterranean lithospheric plates was constructed using interpretations of seismic measurements and borehole data. Structural maps of three principal interfaces, elevation, top basement and the Moho, were constructed for the area studied. This area includes the African, Sinai and Arabian plates, the Herodotus and the Levant marine basins and the Nile sedimentary cone. In addition, an isopach map of the Pliocene sediments, as well as the contemporaneous amount of denuded rock units, was prepared to enable setting up the structural map of the base Pliocene sediment. Variable density distributions are suggested for the sedimentary succession in accord with its composition and compaction. The spatial density distribution in the crystalline crust was calculated by weighting the thicknesses of the lower mafic and the upper felsic crustal layers, with densities of 2.9 g/cm 3 and 2.77 g/cm 3, respectively. Results of the local (Airy) isostatic modeling with compensation on the Moho interface show significant deviations from the local isostasy and require variable density distribution in the upper mantle. Moving the compensation level to the base of the lithosphere (∼ 100 km depth) and adopting density variations in the mantle lithosphere yielded isostatic compensation (± 200 m) over most of the area studied. The spatial pattern obtained of a density distribution with a range of ± 0.05 g/cm 3 is supported by a regional heat flux. Simulations of the flexure (Vening Meinesz) isostasy related to the Pliocene to Recent sedimentary loading and unloading revealed concentric oscillatory negative and positive anomalies mostly related to the Nile sedimentary cone. Such anomalies may explain the rapid subsidence in the Levant Basin and the arching in central Israel, northern Sinai and Egypt during Pliocene–Recent times. Comparison between the observed (Bouguer) gravity and the calculated gravity for the constructed 3-D lithospheric structure, which has variable density distributions, provided a good match and an independent constraint for the large-scale structure suggested and confirmed an oceanic nature for the Levant Basin lithosphere.

Relative sea‐level changes, glacial isostatic modelling and ice‐sheet reconstructions from the British Isles since the Last Glacial Maximum

AbstractWhile contributing <1 m equivalent eustatic sea‐level rise the British Isles ice sheet produced glacio‐isostatic rebound in northern Britain of similar magnitude to eustatic sea‐level change, or global meltwater influx, over the last 18 000 years. The resulting spatially variable relative sea‐level changes combine with observations from far‐field locations to produce a rigorous test for quantitative models of glacial isostatic adjustment, local ice‐sheet history and global meltwater influx. After a review of the attributes of relative sea‐level observations significant for constraining large‐scale models of the isostatic adjustment process we summarise long records of relative sea‐level change from the British Isles and far‐field locations. We give an overview of different global theoretical models of the isostatic adjustment process before presenting intercomparisons of observed and predicted relative sea levels at sites in the British Isles and far‐field for a range of Earth and ice model parameters in order to demonstrate model sensitivity and the resolving power available from using evidence from the British Isles. For the first time we show a good degree of fit between relative sea‐level observations and predictions that are based upon global Earth and ice model parameters, independently derived from analysis of far‐field data, with a terrain‐corrected model of the British Isles ice sheet that includes extensive glaciation of the North Sea and western continental shelf, that does not assume isostatic equilibrium at the Last Glacial Maximum and keeps to trimline constraints of ice surface elevation. We do not attempt to identify a unique solution for the model lithosphere thickness parameter or the local‐scale detail of the ice model in order to provide a fit for all sites, but argue that the next stage should be to incorporate an ice‐sheet model that is based on quantitative, glaciological model simulations. We hope that this paper will stimulate this debate and help to integrate research in glacial geomorphology, glaciology, sea‐level change, Earth rheology and quantitative modelling. Copyright © 2006 John Wiley & Sons, Ltd.

Sea-level during the early deglaciation period in the Great Barrier Reef, Australia

Ooids samples recovered from the Capricorn Channel in the southern Great Barrier Reef (GBR) were analyzed to study paleo sea-level during the late glacial period. Their ages and depth distribution were compared with numerical predictions obtained using a detailed glacio-hydro isostatic model to examine the reliability of the ice model. A step-wise dissolution technique was used to remove secondary carbon contamination and determine the exact timing of formation. The dating results indicate that ooid formation took place around 16,800 cal. yr BP, immediately prior to a period of accelerated melting of the global ice sheets, the Meltwater pulse 1a event. Sea-level predictions obtained using rheological parameters optimized for the Australian coast are consistent with the radiocarbon-derived ooid depth–age data, which suggest that at 16.8 cal. ka sea-level in the southern GBR was 100 m below its present height.

The isostatic compensation of the Azores Plateau: A 3D admittance and coherence analysis

The compensation of the Azores Plateau is re-examined by means of a 3D admittance study involving computations of the admittance between the bathymetry and (1) the geoid, (2) the free air gravity and (3) the mantle Bouguer anomalies. The geoid to bathymetry relationship, rather than being analysed in the space domain, is studied in the spectral domain. In this way, the information related to the flexural response of the lithosphere is retained in the geoid to bathymetry signal and can be compared to that of the gravity to bathymetry. We find that the anomalously shallow depths of the Azores Plateau are not due to dynamic forces sustained by mantle upwelling. The Plateau is supported by a thickened crust, which mainly results from large volumes of accreted extrusives and consequent deflection of the underlying elastic plate. Both the free air gravity and the mantle Bouguer admittance point to a flexural isostatic model with a Moho depth of 12 km and an elastic thickness in the range of 3–6 km. However, the analysis of the coherency between bathymetry and the mantle Bouguer anomaly indicates that buoyant material at the base of the crust partially accounts for the uplift of the Plateau. In our best-fitting model, the average elastic thickness is 4 km and the amplitude of the buoyant load at the Moho is 1 / 3 of that of the surface volcanic load. Buoyancy forces at the Moho may arise from underplated material resulting from subcrustal plutonism.

Isostatic response of the Alula-Fartak and Owen transforms in the Eastern Gulf of Aden and the adjoining Arabian Sea

SUMMARY The Alula-Fartak and Owen transforms are the active parts of major fracture zones with a distinct topographic expression in the Eastern Gulf of Aden and the Arabian Sea, respectively. While the Alula-Fartak transform offsets the Sheba Ridge by about 180 km and is associated with a broad steep-sided valley with a relief of nearly 3.5 km, the Owen transform offsets the Carlsberg Ridge by nearly 300 km and is associated with a broad step-like valley surrounded by deeper water depths. The gravity and topography data along several profiles selected across these two transforms have been analysed using cross-spectral analysis in order to investigate their isostatic compensation. The observed admittance estimates have been compared with three theoretical isostatic compensation models, two local compensation models (Airy I and II) and one regional compensation (plate) model. Comparing the longer wavelength admittance estimates suggests that the regional compensation model gives the best fit for both the Alula-Fartak transform and the Owen transform, with effective elastic thickness (Te) of 5 km and slightly less than 10 km, respectively. For the Alula-Fartak transform, the Airy II model might also be acceptable, though with large scatter in the observed values: it suggests a mean value of 9 km for the mantle layer with a 6 km thick crust. For the Owen transform, on the other hand, the two local compensation models failed. The difference in Te estimate between the two transforms could be ascribed to differences in thermal structure arising from their varied tectonic history. A comparison with the isostatic response estimates of transform/fracture zones along the slow-spreading Mid-Atlantic Ridge suggests that the regional compensation model is generally applicable for transform/fracture zone topography along such mid-ocean ridges.

Flexural and gravity modelling of the Mérida Andes and Barinas–Apure Basin, Western Venezuela

The kinematic evolution of the Barinas–Apure Basin and the southern Mérida Andes from Lower Miocene to the Present is numerically modelled using flexural isostatic theory and geophysical and geological data. Two published regional transects are used to build up a reference section, which is then used to constrain important parameters (e.g. shortenings and sedimentary thicknesses) for the flexural modelling. To control the location of the main fault system in the flexural model earthquake information is also used. The estimated flexural elastic thickness of the South American lithosphere beneath the Barinas–Apure Basin and the Mérida Andes Range is 25 km. The value for the final total shortening is 60 km. The flexural isostatic model shows that the Andean uplift has caused the South American lithosphere subsidence and the development of the Barinas–Apure Basin. In addition, gravity modelling was used to understand deep crustal features that could not be predicted by flexural theory. Consequently, the best-fit flexural model is used to build a gravity model across the Mérida Andes and the Barinas–Apure Basin preserving the best-controlled structural features from the flexural modelling (e.g. basin wavelength and depth) and slightly changing the main bodies density values and deep crustal structures. The final gravity model is intended to be representative of the major features affecting the gravity field in the study area. The predicted morphology in the lower crustal level of the final gravity model favours the hypothesis of a present delamination or megathrust of the Maracaibo crust over the South American Shield. This process would use the Conrad discontinuity as a main detachment surface within an incipient NW dipping continental subduction.

A review of possible eustatic, isostatic and tectonic contributions in eight late-Holocene relative sea-level histories from the Mediterranean area

This paper consists of a comparison between eight late-Holocene sea-level histories investigated by the author in different Mediterranean areas and sea-level predictions in the same areas made by global isostatic models. The areas include three regions that are generally considered as tectonically relatively stable: (1) the southern coast of France, (2) Sardinia, and (3) the southern coasts of Tunisia, where late-Holocene evidence may be either of submergence, or of emergence. Also considered are: (4) a subsidence region in the northern Adriatic, and actively uplifting areas: (5) in Calabria, and (6) in Nisyros Island (Greece). Lastly, case studies in areas affected by repeated coseismic vertical displacements include: (7) western Crete and Antikythira Island in the Hellenic Arc, and (8) the Levant coasts of Turkey, Syria and the Lebanon. In each case the question of whether the evidence available may or may not be consistent with gradual isostatic or eustatic displacements has been explored. It appears that in non-tectonic areas the hydro-isostatic effects have been overestimated (Sardinia) or underestimated (southern Tunisia) by the same models. In the northern Adriatic, the closest Mediterranean area to the former Scandinavian ice sheet, glacio-eustatic effects are suspected to be almost absent. Our analysis failed to quantify isostatic effects in areas of rapid tectonic uplift (Calabria and Nisyros), but rejected predictions of significant isostatic subsidence in the Hellenic Arc and on the Levant coast. Finally, several data from tectonic and non-tectonic areas are consistent with nearly stable global eustasy since 6000 BP, thus challenging the assertion of significant additional melting of Antarctica after the complete melting of the former Northern Hemisphere ice caps.

The Paranapanema Lithospheric Block: Its Importance for Proterozoic (Rodinia, Gondwana) Supercontinent Theories.

This work considers the tectonics of the southeastern portion of the South American Platform based on new geological and geophysical grounds. For the last decade, only three (Amazonic, São Francisco and La Plata) of the many other cratonic blocks have been attributed/remarked to the South America portion for most of the usual Rodinia reconstitutions. The possibility of the existence of other blocks has rarely been mentioned. The postulation of the presence of a considerable Paleoproterozoic (pre-Brasiliano) fragment as part of Paraná Basin basement is highly probable. In order to infer the basement structure of Paraná Basin, previous to the sedimentation process, an isostatic modeling was applied to a large-scale gravity survey looking to correlate topographic and gravity anomalies caused by sub-surface loads. The Bouguer anomaly obtained from the gravity survey represents the crustal contribution of crystalline basement, in addition to the sedimentary and volcanic layers of the basin. Following the isostatic modeling and the basin load stripping, the residual anomaly allows observing similarities between the basement gravity signature and outcropping units. Besides, the stress pattern of the two earlier events obtained through the back stripping analysis presents a geographically coincident maximum, and a new E-SE high emerging for the second event, suggesting continuous change of the stress field as a precursor for South American plate rotation. The evident correlation between gravity highs and main attenuation suggests the presence of some pre-existing suture zones. The weakened lithosphere during Ordovician and Carboniferous provided the magma conduits to form in Early Cretaceous tectonic stress field pattern. The resultant mosaic of gravity blocks and the main faults site give support to the presence of this cratonic Proterozoic unit, here on referred to as the Paranapanema Block, which had been neglected in most of the models reported for the reconstruction of Gondwana (and Rodinia).

Delimitation of the Paranapanema Proterozoic block: A geophysical contribution

This study focuses on the basement structure of the Parana Basin in South America, based on geological and geophysical data. It is a large intracratonic basin formed from the Late Ordovician until the Cretaceous, when a sequence of continental flood basalts eruptions covered the entire basin, preceding the break-up of Western Gondwana. Isostatic modeling was applied to large gravity surveys comprising more than 12,000 gravity stations. The residual Bouguer anomaly pattern, representing the crustal contribution of the crystalline basement, as well as the sedimentary and volcanic layers of the basin, reveals similarities between the basement gravity signature and the exposed rock. The stress patterns of the Late Ordovician and Cretaceous tectonic events present a geographically coincident maximum, and the correlation between gravity highs and the main attenuation (beta factor) suggests the presence of some preexistent suture zones. The resultant mosaic of gravity blocks and the location of major faults give support to the presence of an important Proterozoic cratonic feature, here referred to as Paranapanema block.

Gravity field and isostatic state of Ethiopia and adjacent areas

Over 35,000 onshore and offshore gravity stations have been compiled in order to test isostatic models against geologic structures over a part of the Afro–Arabian shield. The area of Ethiopia covers an important part of this system because it contains the major section of the ≈5000 km Afro–Arabian rift and includes the transition between the Arabo-Nubian-Shield (ANS) and the Mozambique Belt (MB). Isostatic residual anomalies have been calculated using both Airy and Vening-Meinesz (flexural rigidity D = 10 22 Nm) models. The isostatic residual anomalies outline the major Precambrian belts, the Cenozoic rifts and associated major structures. Positive residual anomalies associated with the main Ethiopian Rift (MER) and Kenyan rift systems could be the expressions of an axial intrusive body and swarms of local faults and fractures. The residual anomalies indicate relative stability in the MER and increased tectonic activity in the areas of the Red Sea, Gulf of Aden and Afar. Near-zero isostatic residuals flank the MER and Kenya rifts and are found within the Danakil Alps and some plateau regions. The small mean isostatic residual anomaly (about 8 mGal) and the isostatic analysis show a slight positive bias indicating under compensation. The undercompensation may imply that there are upper crustal features that are not compensated regionally (probably supported by the rigidity of the lithosphere) and isostatic disequilibrium in the region. Therefore, the high topography of Ethiopia and East African plateau is partly compensated by thicker crust (broad negative isostatic regional anomaly) and partly by dynamic forces. The results of the qualitative interpretation form the basis of continuing three-dimensional gravity modelling and quantitative analysis that also integrates data from eastern Sudan.

Present-day tilting of the Great Lakes region based on water level gauges

By using monthly mean water levels at 55 sites around the Great Lakes, a regional model of vertical crustal motion was computed for the region. In comparison with previous similar studies over the Great Lakes, 15 additional gauge sites, data from all seasons instead of the 4 summer months, and 8 additional years of data were used. All monthly water levels available between 1860 and 2000, as published by the U.S. National Ocean Survey and the Canadian Hydrographic Service, were used. For each lake basin, the vertical velocities of the gauge sites relative to each other were simultaneously computed, using the least-squares adjustment technique. Our algorithm solves for and removes a monthly bias common to all sites, as well as site-specific biases. It also properly weighs the input water levels, resulting in a realistic estimation of the uncertainties in tilting parameters. The relative velocities obtained for each lake were then combined to obtain relative velocities over the entire Great Lakes region. Finally, the gradient of the relative rates for the regional model was found to agree best with the ICE-3G global isostatic model of Tushingham and Peltier, whereas the ICE-4G gradients were too small around the Great Lakes.

Regional–residual Gravity Field Separation in the Central Andes using Global Geopotential Models

Traditional methods of regional?residual gravity field separation typically involve high-pass filtering, low-order polynomial fitting or computations using isostatic models. All of these methods are susceptible to ambiguity and subjectivity in the selection of filter parameters, polynomial degree and isostatic model. Global Geopotential Models (GGMs), on the other hand, provide long-wavelength gravity data that are based on observations. Therefore, they have the potential to be used to more objectively define the regional gravity field and to give residual anomalies with reduced ambiguity. We have examined residual gravity anomalies in the Central Andes computed using a regional field defined by the recent EIGEN?GRACE01S satellite-only GGM. The resulting residual anomalies show significant correlations with the active volcanic arc and the geometry of the subducting Nazca plate. These results suggest that GGMs have a place in regional gravity interpretation, but the advantages over existing techniques remain to be thoroughly tested.

A new isostatic model of the lithosphere and gravity field

Based on the analysis of various factors controlling isostatic gravity anomalies and geoid undulations, it is concluded that it is essential to model the lithospheric density structure as accurately as possible. Otherwise, if computed in the ‘classical’ way (i.e. based on the surface topography and the simple Airy compensation scheme), isostatic anomalies mostly reflect differences of the real lithosphere structure from the simplified compensation model, and not necessarily the deviations from isostatic equilibrium. Starting with global gravity, topography and crustal density models, isostatic gravity anomalies and geoid undulations have been determined. The initial crust and upper-mantle density structure has been corrected in a least squares adjustment using gravity. To model the long-wavelength (>2000 km) features in the gravity field, the isostatic condition (i.e. equal mass for all columns above the compensation level) is applied in the adjustment to uncover the signals from the deep-Earth interior, including dynamic deformations of the Earth’s surface. The isostatic gravity anomalies and geoid undulations, rather than the observed fields, then represent the signals from mantle convection and deep density inhomogeneities including remnants of subducted slabs. The long-wavelength non-isostatic (i.e. the dynamic) topography was estimated to range from –0.4 to 0.5 km. For shorter wavelengths (<2000 km), the isostatic condition is not applied in the adjustment in order to obtain the non-isostatic topography due to regional deviations from classical Airy isostasy. The maximum deviations from Airy isostasy (−1.5 to 1 km) occur at currently active plate boundaries. As another result, a new global model of the lithosphere density distribution is generated. The most pronounced negative density anomalies in the upper mantle are found near large plume provinces, such as Iceland and East Africa, and in the vicinity of the mid-ocean ridge axes. Positive density anomalies in the upper mantle under the continents are not correlated with the cold and thick lithosphere of cratons, indicating a compensation mechanism due to thermal and compositional density.

3D modelling of flexural isostatic deformation

Modelling of the isostatic loading of the earth's crust in three dimensions is a difficult problem due to the length scales involved, the lack of scalability of the underlying equations and the slow convergence of the solution under conventional techniques. In this paper, a new method to solve the three-dimensional (3D) flexure equation has been developed. The long-standing challenge in numerically modelling flexural isostasy at large scale and high rigidity is addressed. The program is capable of modelling both local and regional isostatic compensation. Compared with other schemes, the isostatic model presented here is more robust and computationally efficient.

Regional three‐dimensional gravity modelling of the NE Atlantic margin

AbstractA series of three‐dimensional models has been constructed for the structure of the crust and upper mantle over a large region spanning the NE Atlantic passive margin. These incorporate isostatic and flexural principles, together with gravity modelling and integration with seismic interpretations. An initial isostatic model was based on known bathymetric/topographic variations, an estimate of the thickness and density of the sedimentary cover, and upper mantle densities based on thermal modelling. The thickness of the crystalline crust in this model was adjusted to equalise the load at a compensation depth lying below the zone of lateral mantle density variations. Flexural backstripping was used to derive alternative models which tested the effect of varying the strength of the lithosphere during sediment loading. The models were analysed by comparing calculated and observed gravity fields and by calibrating the predicted geometries against independent (primarily seismic) evidence. Further models were generated in which the thickness of the sedimentary layer and the crystalline crust were modified in order to improve the fit to observed gravity anomalies. The potential effects of igneous underplating and variable upper mantle depletion were explored by a series of sensitivity trials. The results provide a new regional lithospheric framework for the margin and a means of setting more detailed, local investigations in their regional context. The flexural modelling suggests lateral variations in the strength of the lithosphere, with much of the margin being relatively weak but areas such as the Porcupine Basin and parts of the Rockall Basin having greater strength. Observed differences between the model Moho and seismic Moho along the continental margin can be interpreted in terms of underplating. A Moho discrepancy to the northwest of Scotland is ascribed to uplift caused by a region of upper mantle with anomalously low density, which may be associated with depletion or with a temperature anomaly.

Lithospheric deformation beneath the Altyn Tagh and West Kunlun faults from recent gravity surveys

New gravity and topographic elevation data crossing the Altyn Tagh and West Kunlun faults in northern Tibet are used to test key features of a recently proposed tectonic model for the northern boundary of the Tibetan Plateau. The observations, collected in 1997 and 1998 at 468 stations along three profiles, were converted to Bouguer gravity anomalies to constrain flexural models for isostatic compensation of the large relief associated with these faults. Initially, we failed to reproduce the main features of the gravity anomalies with any isostatic model that assumes that the main contribution to the observed gravity anomalies is from the flexure of the Moho. By integrating sedimentary information derived from exploration seismology in the Tarim and Qaidam basins, we obtained satisfactory fits to the data using simple models of isostasy. No elastic strength across the Altyn Tagh is required to fit the gravity data, suggesting that the fault breaks the entire lithosphere beneath it and has negligible thrust component currently or in the past. This result is consistent with tectonic models that create the thickened crust of northern Tibet through thick‐skinned thrust sheets progressively overriding Asia to the northeast as the Altyn Tagh, behaving as a classic transform fault, propagates in that direction. Farther west, the gravity observations across the West Kunlun are best explained by significant underthrusting of the high topography by an elastic plate with effective thickness between 30 and 40 km, in agreement with geologic interpretation and modeling of earlier, but very sparse, gravity observations.

Isostatic response of the earth's crust derived by inverse isostasy

Postulate that the density anomaly is proportional to the earth's radius vector so that it is linearly related to the topography by a convolution of the topography and an isotropic kernel function. Accordingly, one can prove that the attraction of the compensating masses is also a convolution of the topography and an isotropic isostatic response function. Such an isostatic response function can be determined by deconvolution. The paper gives the derivation of such a deconvolution by means of spherical harmonics. A practical determination of the isotropic isostatic response function needs the harmonic analysis of both the topography and the attraction of the compensating masses. Applying the principle of inverse isostasy, by which we aim to achieve zero isostatic anomalies, then the attraction of the compensating masses equals the Bouguer anomalies with an opposite sign. The harmonic analysis of the Bouguer anomalies is thus a combination of the harmonic analysis of the topographic potential and the already existed global reference models. A practical application has been carried out using EGM96 and GPM98CR geopotential earth models as well as TUG87 and TBASE digital height models. The results show that the estimated isotropic isostatic response functions behave similarly as that given by the exact bending curve of the earth's crust represented by the Kelvin function kei x. This shows that the isostatic response of the earth's crust computed by direct isostasy using the most realistic isostatic model (modified Vening Meinesz isostatic model with Kelvin function kei x as the exact bending curve) matches the isostatic response of the earth's crust derived by inverse isostasy.

An isostatically compensated gravity model using spherical layer distributions

A new isostatic model for the Earth's gravity field is presented based on a simple hypothesis of layers approximating constant density contrasts. The spherical layer distribution used to describe the hydrostatic equilibrium of the Earth's masses leads to a new set of spherical harmonic coefficients for the gravitational potential. First attempts to quantify the information content of these coefficients led to the outcome that they seem to explain the observed gravity field for a certain wavelength band, while they are insufficient for short and very long wavelengths. A synthesis of the derived coefficients over specific degree ranges provided a computation of band-limited geoid undulations on a global scale. The association of these potential quantities with known tectonic structures, such as the topography of the core-mantle boundary, strengthens the belief that the interpretation of Earth gravity models, especially those arising from global digital elevation models, should be considered in close relation with deep-Earth structure.

Formation of the Maturín Foreland Basin, eastern Venezuela: Thrust sheet loading or subduction dynamic topography

The Maturín Basin in eastern Venezuela is considered a good example of a peripheral foreland basin. Earthquake and tomographic data indicate that eastern Venezuela is affected by the oblique subduction of the South American Plate underneath the Caribbean Plate. New forward flexural isostatic modeling of eastern Venezuela has been carried out in order to determine whether the Maturín Basin was generated purely by thrust sheet loading from the Serranía and Monagas Foreland Thrust Belts. A sequence of forward models from middle Miocene to Present was generated for 3 profiles across the Serranía del Interior Thrust Belt, the Monagas Foreland Thrust Belt, and the Maturín Foreland Basin. The predictions of these models are constrained using seismic reflection and well data. The flexural isostatic modeling shows that thrust sheet loading associated with the Serranía del Interior and Monagas Foreland thrust belts is insufficient to generate the observed subsidence within the Maturín Basin. Dynamic fluid flow modeling of subduction related dynamic topography of eastern Venezuela has been used to investigate the influence of South American Plate subduction on the generation of the accommodation space observed in the Maturín Basin. Fluid flow modeling of subduction related dynamic topography suggests that the subduction of the South American lithospheric mantle caused downward deflection of the South American crust affecting the Maturín Basin and the Serranía Thrust Belt. This modeling suggests that the Maturín Basin subsidence has two components: 55% related to thrust sheet loading and 45% driven by continental subduction.